Yahoo CEO Marissa Mayer will face a $10 billion decision in a few months.

She already has made many changes since taking over nearly two years ago, but all the internal reshuffling and deal-making has merely been a prelude to her biggest test.

The pivotal moment in Mayer’s tenure will come after Alibaba Group, China’s e-commerce leader, completes one of the biggest initial public offerings of stock in U.S. history. The IPO triggers a provision requiring Yahoo Inc. to sell about 40 percent of its stake in Alibaba. The sale is expected to generate a major windfall that will intensify the pressure on Mayer to revive Yahoo’s revenue growth after years of lethargy.

“This is Marissa’s moment of reckoning,” says Moshe Cohen, a Columbia University business professor who has been tracking Yahoo’s ties with Alibaba.

Mayer acknowledged as much Wednesday during an appearance in New York at a conference hosted by TechCrunch.

Only about one-quarter are performing proficiently or better in math and just 4 in 10 in reading. And they’re not improving, the report says, reinforcing concerns that large numbers of today’s students are unprepared for either college or the workplace.

Scores on the 2013 exam in both subjects were little changed from 2009, when the National Assessment of Educational Progress was last given to 12th-graders. The new results, released Wednesday, come from a representative sample of 92,000 public and private school students.

The report follows the just-released and seemingly more encouraging research that U.S. high school graduation rates in 2012 reached 80 percent, a record.

One possible explanation is that lower-performing students who in the past would have dropped out of school are now remaining in the sampling of students who take the exam, said John Easton, acting commissioner of the Education’s Department’s National Center for Education Statistics.

LAGOS, Nigeria

Official: ‘Hundreds’ killed in attack

Islamic militants killed hundreds of people in an attack on a border town in Nigeria’s remote northeast, escalating the country’s violent insurrection in which more than 270 schoolgirls have been kidnapped.

As many as 300 people were killed when a band of extremists attacked the town of Gamboru Ngala, on Nigeria’s border with Cameroon, according to local press reports. The attack and hundreds of casualties were confirmed Wednesday by Borno state information commissioner Mohammed Bulama who spoke to The Associated Press by telephone Wednesday. Shops and homes were set ablaze and razed in the attack, he said.

The news of the attack adds to Nigeria’s growing crisis from the Islamic extremists’ violent campaign of bombings, attacks and abductions. The militant Boko Haram rebels are holding captive 276 teenage students, after abducting them from their boarding school in Chibok, also in northeastern Borno state.

In the attack on Gamboru Ngala the militants sprayed gunfire into the crowds of people at a busy market that was open Monday night when temperatures cool in the semi-desert region, reported ThisDay newspaper.

Nigerian federal Senator Ahmed Zannah said the attack lasted about 12 hours, according to the newspaper. The insurgents set homes on fire and gunned down residents who tried to escape from the flames, reported the paper.

NAIROBI, Kenya

Extremist leader surfaced in 2010

Tugging on his winter hat, the Islamic militant leader declared with a sneer: “I will sell women.”

His name is Abubakar Shekau, commander of Nigeria’s most feared terror group, Boko Haram. His threat to sell nearly 300 teenage school girls abducted from a school in remote northeast Nigeria came in a grainy video released this week.

The warning has vaulted the wanted terror leader into global headlines.

Even before the April 15 kidnapping, the U.S. government was offering up to a $7 million reward for information leading to the arrest of Shekau, whom the U.S. has labeled a specially designated global terrorist.

“He’s isolated, he’s increasingly extremist and he’s delusional enough to think he could bring down the Nigerian state,” said J. Peter Pham, the director of the Africa Center at the Washington-based Atlantic Council, who wrote a 2012 report called “Boko Haram’s Evolving Threat.”

WASHINGTON

Obama to unveil emission limits

Within weeks, President Barack Obama’s administration is set to unveil unprecedented emissions limits on power plants across the U.S., much to the dismay of many Democratic candidates who are running for election in energy-producing states. Fearful of a political backlash, they wish their fellow Democrat in the White House would hold off until after the voting.

But Obama can’t wait that long.

Unlike the Keystone XL oil pipeline, whose review the administration has delayed, probably until after November’s elections, the clock is ticking for the power plant rules — the cornerstone of Obama’s campaign to curb climate change. Unless he starts now, the rules won’t be in place before he leaves office, making it easier for his successor to stop them.

So even though the action could bolster Republican attacks against some of this year’s most vulnerable Democrats, the administration is proceeding at full speed. Obama’s counselor on climate issues, John Podesta, affirmed that the proposal will be unveiled in early June — just as this year’s general election is heating up.

“Having this debate now will only injure Democrats,” said Hank Sheinkopf, a longtime Democratic strategist. “Democrats are in trouble. The best thing when you’re in trouble is to avoid further controversy.”

ST. PETERSBURG, Fla.

Authorities: Fire intentionally set

Police in Florida say the fire at the home of a former tennis star was intentionally set and a family of four was killed.

Hillsborough County Sheriff’s Col. Donna Lusczynski said Wednesday that two adults and two teenagers were killed in the mansion belonging to tennis player James Blake. He was not home at the time and was renting the house to the family.

Lusczynski said the scene was “unusual.” She says officials don’t know how the fire was set.

She added that there were “various fireworks” throughout the home and that two of the bodies appeared to have “upper body trauma,” but she didn’t give any more details.

Authorities say the bodies in the home have not been positively identified.

WASHINGTON

GOP moves on Benghazi probe

House Republicans on Wednesday moved toward an election-year special investigation of the deadly attack on a U.S. diplomatic post in Libya, brushing aside Democratic concerns over the panel’s scope and composition. The Obama administration, meanwhile, accused Republicans of “political motivation” after they issued a fundraising email linked to the Benghazi probe.

Ahead of a Thursday vote to rubber-stamp the establishment of the Benghazi select committee, House Speaker John Boehner vowed that the examination would be “all about getting to the truth” of the Obama administration’s response to the attack and not be a partisan, election-year circus. “This is a serious investigation,” he said, accusing the president and his team of withholding the true story of how militants killed Ambassador Chris Stevens and three other Americans on Sept. 11, 2012.

Democrats pondered a boycott while waiting for Boehner to respond to demand from Minority Leader Nancy Pelosi that he scrap his plan for a committee of seven Republicans and five Democrats. Democrats insisted membership should be evenly split, and urged time and cost constraints for a forum they likened to a “kangaroo court” designed only to drum up GOP support ahead of the November elections.

Under Boehner’s legislation, the select panel “can go on forever,” Rep. Xavier Becerra, D-Calif., told reporters. “The amount of money they can spend is undefined and can be unlimited.”

SAN FRANCISCO

Alibaba preps blockbuster U.S. sale

Alibaba Group, the king of e-commerce in China, is dangling a deal that could turn into one of the biggest IPOs in history.

In a long-awaited move Tuesday, Alibaba filed for an initial public offering of stock in the U.S. that could surpass the $16 billion that Facebook and its early investors raised in the social networking company’s IPO two years ago.

Alibaba’s paperwork says it will raise at least $1 billion, but finance professionals believe that is a notional figure to get the IPO process rolling and say that the Chinese company’s ambitions for the share sale are much richer.

“This is going to be the granddaddy of all IPOs,” predicted Sam Hamadeh, CEO of PrivCo, which researches privately held corporations.

Although it’s not well-known in the United States, Alibaba is an e-commerce powerhouse that makes more money than Amazon.com Inc. and eBay Inc. combined. It has helped drive the rise of e-commerce in China, a transformation that has given millions of households greater access to clothes, books and consumer electronics in a society that in the 1980s still required ration tickets for some supermarket items.